Telephone system.



T. G. MARTIN.

TELEPHONE SYSTEM.

APPLICATION FILED IAUG. H, 1913.

EflmTIAMQ Patented May 22, 1917.

?SHEETSSHEET 1.

HQ. x

H .l H? B H V WITNESSES ivj/z/vmfi T. G. MARTIN.

TELEPHONE SYSTEM.

APPLICATION FILED AUG. 11, 1913.

Patented May 22,1917.

7$HEETS-SHEET 2.

1 WITNESSES fiTTOR/VEYS. I

'T. G. MARTIN.

TELEPHONE SYSTEM.

m APPLICATION FILED AUG. H, 1913. 1,%% (A (41, Patented May 22, 1.917.

I $HEETSSHEET 3- htented May 22, 191?? ISHEETS-SHEET 4- 5/1/27W55555" I fiK/VEVI/TOR' MW I zwmzzwu T. G. MARTIN.- TELEPHONE SYSTEM.

I I I APPLICATION HLED AUG-111913 1,Q%7,&74n Patented May 22, 1917.

' I TSHEETS-SHEET 5- T. G. MARTIN. TELEPHONE SYSTEM APPLIC ATKO N FiLED AUG. 11, 1913- Patented May 22, 1917.

TSHEETSSHEET 6- W WW Z W/MEE WTNESSES .u MEL- T. G. MARUN.

TELEPHONE SYSTEM. APPLICATION FILED AUG. 11, 1913.

,QZKATQM Patented May 22-, 1917 ZSHEETSSHEET I.

\MMMEIIHHB- W A/ 1 v UN @ATIE% ATNT @FJWE.

TALBOT GIMABTIN. OF CHICAGO, ILLINOIS, ASSIGIIOR 'IO AUTOMATIC ELECTRIC COM- TELEPHGNE SYSTEM.

the following is a specification.-

.\ly invention relates to improvements in telephone systems. and more particularly to improvedmeans for handling long distance or toll calls in connection with an automatic telephone system. When a long distance call comes into an automatic exchange, it

comes in on a manual board and the operator. upon learning the number ot the subscriber desired. extends the connection through a suitable (H' 5l circuit to a selector switch in the automatic exchange and then, by operating her calling device. extends the connection through the automatic switches to the subscriber called for in the usual manconnection that it is desirable to advise the It is desirable to give these long distance calls preference over local calls. as trunk lines between cities should not be. tied up on a single call any longer than necessary; It ot'ten times happens that the operator who receives the long distance call linds that the desiru l'called subscribefs line is busy. 'ith the ordinary connector switches employed it is impossible for the operator to obtain a connection with this busyline. It is desirable. however. that in such case. the operator be able to advise the desired subscriber who is thus involved in another connection that he is wanted for a long distance call. In order to accomplish this purpose I provide a special l'orm of connector switch byhwhich the operator can-make connection with this busv line and advise the. subscriber. ot the desired information.

further ob ect of my invention is to provide the operator with means whereby she can ascertain whether or not a line is' engaged in a'local connectionfor in another long distance connection. ()t course.it a line is already engaged in.a long distance connection it would be inadvisa le and undesiral'ile to break in on this connection and advise the subscriber that he is want'd for another long distance connection- It is only when 'tle subscriber is involved in a local subscriber that he is wanted for a long distance connection. so that the subscribers can Specification of Letters Patent.

Application filedl August 11. 1913. Serial No. 784,097.

Patented May 22, 191?.

break the local connection and permit the completion of the long distance connection;

I therefore provide means for giving to the* operator distinctive forms of busy signals. so that the operator can tell whether the busy line is a calling automatic'line or a called automatic line involved in a local connection, or a called automatic line inv olved in a manual or long distance connection.

further specific object of my invention is the provision of means whereby, when a line is in use. the multiple private contacts of the line'are connected to ground through oneot' a plurality of busy signaling ntachines. depending upon whether. the line is an automatic calling line or a called line involved in a local automaticconnection. or one involved in a long distance manual connection.

In order that my invention may he more clearly umlerstood. I have itlustrated, in diagrammatic form, a telephone system which embodies the features of my invention. In this connection I have chosen to illustrate an automatic. system involving switches of certain well-lnu'nvn types, togetheravith manual apparatus which is em ployed tor establishing'toll' connections, which is likewise ot' a well-known form. My invention. however. is equally as well adapted for use with other forms of auto; matic switches and cordcircuits, and the present system is merely-tor the purpose of illustrating one specific embodiment of my invention. i v

In the accompanying drawings Figure 1 is a. diagrammatic layout of a telephone system in connection with/which I have chosen to illustrate my invention.v

Figs. '3 and 23 show a'complete connection between twonutoma'tic subscribers stations in said systenl.

Fig. I shows a' manual telephone line and operators cord circuit.

Fig. 5') shows a selector switch circuit for I second lc vel a plurality o'l: li'perators' positions \Y. .\t 'l" and T are shown groups of suhstations T the lines of each oi which terminate in an answering ja l: .l on one operators position \V' and in a multiple jack .1 on each operators position in the usual and welllmown manner. Suitahle cord circuits M are providcal tor est-ahlishing connections.

The. automatic exchange is oi? a. welt lniown type. comprising suhscrihers' individual prcselector switches t. first Ht-lt'tfttu switches i second selector switches l and connector switches ll. in the drawings there are represented two thousands of an exchange of ten thousand lines capacity on a "rate of three to ten. The. suhscrihers stations A are divided into groups A, A, etc., usually of one hundred lines each. On a scale of three to ten, therefore. the three groups A A and A represent one complete thousand and the groups A. A. and A represent another thousand. With each group 01 suhscrihers lines there is as sociated in the entral oilice a group of individual, or line switches C. one for each line, a group of 'lrst selectors E, a group of second selectors F and a group of connectors H. The selector and connector switches represented herein comprise hanks of contacts arranged in horizontal rows or levels, usually ten in numher. These levels are. represented hy horizontal lines which eiltend heneath all the switches of? a group to indicate that the corresponding contacts of all the switches of the group are multipled together. All the line switches hclonging to one group oi suhscrihers" lines have common access to a group ot first, selectors l). The hank contacts of the lirst selectors l) of correspoiuling groups or lumdreds arc multiplcd throughout the dill'erout thousands. The first levcl of these lirst selectors i connected to trunk lines lauling to sctond sclectriir switches l associated with the lirst thousand. the second level ol the lirst selectors is connected to trunk lines leading to second selectors associated with the se ond thousand. etc. The hank contacts ol' all the second selectors l associated with a, given thousand arc multiplcd together and the iirst level is connected to trunk lines leading to connector switches ll. which. have access to the suhscrihcrs lines of the first hundred (11' that thousand the. is connected to trunk lines which have access to the lines oi tllesccolitl hundred. etc. This trunking arrangement of an automatic exchange is in general well known in the art and it is notthought necessary to descrihe it in further detail hcrcin.

In order to form a means o1 communication hetwcen the automatic and manual cxchanges. there is provided a numherol trunk lines leading from multiple jacks .l on the leading to connectors manual exchange to selector switches l in the automatic exchange. which schrctorscorres )ond in tun tion to the suhscrihe *t tirst' J Y a I [he hank contacts o1" selector switches l). the operators selectors l mavhc multipled with those ol' some oi the suhscribers selectors l). as indicated. in addition .to the trunk lines leading from the manual exchange to thc selectors exchange. there are a number of trunk lilies lcading to special connector switches X in the automatic exchange. There is one of these special connectors for each of the groups etc. 'lhesc special eonuc tors.- as will he descrihed later; are used hy the operator only a lter she has called the suhscriher over one of the selectors l and the regular switches in the automatic exchange and found the line husy. 'lhese special connectors ll are adapted to call in on a husy line, so that the operator may inform a husy automatic suhscriher that a manual or long distance suhscriher desires connection with him. v

Although in the ahove description of the system shown in Fig. 1 reference has heen made to an automatic exchange and to a manual exchange. it is to he understood that this does not mean that the manual part of the system is necessarily a separate and distinct exchange. it may he simply a manual switchlmard which is usually installed in automatic exchanges for the purpose of himdling long distance or toll calls. 7

in Figs. 2. 3. l. 5. t and T the diti'crent parts oi" the apparatus are designated hy the same reference characters. in so far as is consistent. as in the diagrammatic Fig. 1.

-'lhc automatic slihstati on (Fig. 2)

comprises the usual receiver .2. transmitter l. ringer 'land condenser 5. living an automatic suhstatiou it is also provided with a suitahle call'sending mechanism for controlling the automatic switches, which mechanism is reprcsenttal diagrannnatically hy a pair of impulse springs (Land't' and an impulse wheel 8, which latter may he con-' trolled in a well-known manner through the mcdilun ot a dial provided with linger holes in such away that the impulse springs may he momentarily separated a numher of times corresponding to the respective digits oi the numher ot'. the called suhseriher.

'lhe suhscrihers individual switch is of the general form of suhscrihers switch shown in llritish patent to It. \V. James No. 26.301 of 1906, more closely resemhling,

l in the automatichowever, the particular type shown in Britishpatent to T. (l. Martin No. 1419 of 1910. 'llns line switch comprises, among other details. a plunger (not shown) attached to the 7 end ot a so-ealled plunger arm 9, which arm is controlled lry a magnet 10 comprising an operating winding 11 and a holding wintlmg 12. 'llns magnet also controls the cutj the plunge arm line leading to a first selector 1 16 and cut-otf winding 12.

contact point 26, whereby the connectorpri- .tail s, the selector l rotary magnet 34.

otl' armature 13. The. winding 11 operates both the plunge arm 9 and the armature 13, while the winding 12 is strong enough to only operate the armature 13 and hold f) in its operated position. hen the plunger arm 9 is operated its plunger is forced into a bank otacontact springs, forcing the springs 14,1116 and 17 into engagement with the springs 18, 19, 2t) and 21, respectively. \lthongh only one set of springs, i. 0., 14-21, is shown, each line switch is provided with aplurality of such sets, each forming the terminal of a trunk switch 1C.

connected in multiple to the corresponding springs of all the line switches of the group which is controlled by the master switch I). The switch C is controlled by the subscriber through the medium of the line relay 22. which relay is prefe ably slow acting-that slow to release its armature upon deenergizing.

The master switch D is of the general type of master switches shown in British Patent No. 26,301 of 1906, above referred to, being, however, of the particular type disclosed in said British Patent No. 141!) of 1910. The function of the mastewswitch, as is well known, is to maintain the plungers of all the idle line switches in position to engage the terminal of an idle trunk line. The connector private bank contacts of the line are normally.connected over-a conductor and through the spring 24 and contact point 25'to the bank contact spring pon the operation of the line switch, hmvever, the spring 24 is disengaged from the contactpoint and brought into contact with the inch trunk line is vate bank contacts are connected to ground G through the secondary winding of the trai'islormer ot' a busy Associated with the line A there is shown a call register 28 which is controlled by a double-wound magnet 29.

The first selector switch I is of the general type of selector switches disclosed in l nited States Letters Patent No. 815,321, granted March 13,. and Erickson,

except that'the so-ealled side switch is omitted. Among other dccomprises a bank of contacts arranged in horizontal rows or levels which are adapted to be engaged by a set of \\"ipei':-: 3 0. Ill and 32 carried upon a shaft (not shown), which shatt has vertical movement controlled by the vertical magnet 33 and rotary movement controlled by the The operations of the switch are controlled the d niblc-wound line relay 35. Means for permitting the'switch to be restored to normal position are provided in the release magnet 36, which, upon energizing, with- -called line .is controlled signalingmachine Q.

' lay will be fully described hcreinat'ter.

1906, to Keith. Erickson through the medium 0t draws the retaining pawls from the shaft. The spring contacts 37 and 38 are permitted to close only when the switch shaft has been raised one or more steps from its lowest position. The relays 3E) and 40 are slow acting rela vsthat is. relays which deenergize slowly after their energizing circuits are broken. This slow action is usually obtained by placing a ring of copper around one end of the core of the relay.

The second selector I as well lector I ('Fig. 5) lector I The connector switch ll (Fig. 3) is ol the general type of connector switches disclosed in t'nited States Letters Patent No. 813.17 granted March 13,1906, to Keith. llrickson and Erickson. the circuits. however. being modified to adapt the switch to operate in a system in which the central ollice apparatus is controlled by impulses deliveredover the two sides of the line in series. Like the selectors. the connector is provided with a shaft (not shown)carrying the wipers ll. 42 and t3 and is controlled by the vertical magr t H and the rotary magnctflo. The usual side switch comprising ,the wipers it. 47, 48 and 4.) is controlled by the private magnet 50 in the usual and well-known manner. The magnetiotl is the usual release magnet. 'Ihe.l ine relay 51 is connected with the line' through the reversing springs of a so-called back-bridge relay 52. through the windings of which latter relay the called line is provided with talking current. The ringer relay 253 is th'cmeans through which the application'ot ringing currcntto the .\t Qjand. Q there are shown two busy signaling machines which are connected to the front and back contacts, respectively, of the spring M of a relay 53, which relay is included in the holding circuit'which the connector switch extends back to the selector switches. complete tunctiorL-nnl opemtion of this re- The busy signaling machines. as represented herein, comprise an induction coil or transas the sccluded in a local circuit with two interrin-iters. one of low the other of high frequency. medium of these interruptcrs an intcrmiltent interrupted current is supplied to the primary winding of the transformer, which induces an'intermittent alternating current in the secondary winding. whereby. when said winding. is connected with a subscribefs line. said subscriber is given an intermittent buzzing sound in his receiver. The low l'requency interrupters of the two busy niachines Q and Q have ditl'erent l'reqnencie's. so that the 'ln zzing prodnced by one machine is of a different character than that produced by the other.

a battery and Frequency and lhrou gh the is the same as the se former the primary windingot which is in- The substation A and its individual switch C.,arc in all respects the same as the substation and switch C (Fig '2).

The substation T (Fig. l) is an ordinary .loeal batter manual substation. com n'isin h a. transmitter 5. receiver at). induction coil 57, magneto 5S and ringer 5t). tral ollice the line is provided with the usual answering jack J, one or more multiple jacks J, the line relay (it). cnt-oll' relay (31. line lamp (3'2 and a visual busy signal 3 associated with each multiple jack. The operator's cord circuit M resembles the usual cord circuitemployed in manual systems in that it comprises an answering plug a calling calling and answering supervisory lamps (if) and (iii and suitable relays for con trolling the circuits thereot. The relay (3T in the calling end of the cord is a polarized relay., This cord circuit. as shown. is adapted to complete connection with eithe' another manual substation. such as the substation T.

or with 'a'trunk line leading to the automatic exchange. or with an ordinary common hattery line. 'hen the relay tit-t is in its normal position, the circuits of the relay (3T are adapted for use in connection with a local battery line. or with a trimk line leading to the automatic exchange? but when the relay (38 is energized, the circuits of the relay ()7 are. adapted for use in connection with a common battery manual line or a similar line. f

The trunk lines which lead from the manual switchboard to the automatic exchange. as has been explained in connection with Fig. 1, terminate in a multiple jack .l on the luauual switchboard. lhe sleeve conductors of the jacks J are connected to battery through a relay- (it) which controls the circuit of a visual 'busy signal 70 associated with each multiple jack.

-'lhe trunk hues leading from the manual switchboard to the connector switches N (Figs. 1 alul (3) are. at the manual switchboard end thereof. similar to those which lead to the selector switches l. ,The connector N is in general similar to the connector ll' (Fig. 3). there being. however. certain ,mtulilications in the circuit connections and mode of operation.- as will be tully descri ed hereinafter. The connector ll shown in Fig. 7 is similar to the connector ll. (Fig. 3). with certain nuulitications inthe busy test circuit. which will appear from the detailed description which is'to follow.

ltor the purpose of supplying current for.

*2! to the attery lead St central olliee apparatus and operating the purposes there is shown for talking throughout the drawings a. plurality of oat- .\t the ceu- I hook switch springs relay lirst selector switch ha ving been given, lit will now be explained how connection is cXte'nded from the calling substation A to the called substationA', the number of which latter will be assumed to be. 2220. Since the automatic switching apparatus disclosed herein is in general well known in the art. andis described in the publications hereinabove referred to, its 0pcration will be explained in a more orless general manner. t'pon the removal of the receiver from the switch hook at the substation A preparatory to making a call, the talking circuit of the substation} is bridged across the line comluctors it and TZby-the 73 and it. whereby the circuit of the line relay is closed. This cireuit-exteuds t n ground (i through the springs-75 audli l'tt line T1. substation A. line 72. springs T7 and T3 and the relay 3; to the battery lead 80. thence through the battery l3 to grou nddl. The 2'). upon energizing. closes the circuit ot' the operating winding it. which operates to disconnect .the relay 2:2 from the linethrough the medium of the armature 13. and to thrust the plungerot the switch into the terminal of the trunk before which it is being held by the master switch. whereby the line circuit is extended j through the springs 14 and 18 and 15' and 19 to an idle The line relay 35 of the selector switch i is thereupon energizcd over a circuit extem-ling from ground (Pthrough the. lower windiugot'said relay,

winding of the metermagnet 29. back con-.-

tactot the switching relayspriug Sil in the select( and the upper winding of the line relay 35 to the battery lead 80. The relay 3.). upon energizing. closes the circuit of the relay titlwvhich n turn. upon energizin closes a circuit extending from ground (1* throu h the swings 83. line switch bank springs 20 and 16 and the holding winding 1; to the battery lead 80. The euergization of this windnig serves to hold the switch in its operated position after the circuit of the winding 11 is broken by the relay L"). which dei uergizcs shortly after it" is disconnected from theliue. The euergizacompletes a circuit extending from ground (i to the springs S5. 20.and It and through the right-hand winding of the meter magnet- The curreut in tllis winding is in opposition to the line current llowing through the other winding. and

.tion of the relay 239 at the selector E also i I 12g the magnet is therefore not operated at this euit of the seleetor line relay 35.

level 56f bank eontaets. and

95; upon energizing.

net 34), shatt. eontaet' 3T- "97 and 98 and its own throughlthe secondary winding St; of the usy signaling maehine Q;eontaet point it). spring :24 and the eond'uetor 2 l'pon the closure of the springs 17 and 21 by the operation 'of the switch t. the master switch D operates in a well-known manner to adant-e the plungers ot' the idle line swited-ies to a position opposite an idle trunk line.

Theealling subscriber now operates his -alling device for called number, pulse springs ti momentarily.

whereby the substation lllleaeh time breaking the en'- The relay 3911f theseleetor being slow acting does not dei nergize (luring the vniomentaiy interruptions of its e-ireuit by the relay 33, and consequently, eaeh time the latter relay deinergizes, an impulse is trz'insmitted over the V ('ireuit extending from ground (i through the springs RH and fit). and i l. spring 92 and its front eontaet. relay i and the vertieal magnet 33 to the battery lead 80. The vertieal magnet reeeiy-estwo" impulses over this eireuit and operates to raise the switeh shaft and wipers two steps to aflposition o ":site the seeond row or at the same time the shaft-eontrolled eontaets 37 and 38 are elosed. The slow aeting relay 4t) is'maintained in its energized position eontinuously while-impulsesare being transmitted to the. vertieal inagnetthrough it and. in its energized position. rloses a eireuit from ground (:l' through the springs 13 and fll and the relay to the battery lead 80; The relay i'orms a lot-king eireuit for itself extending from ground (1" at the relay thithrough the springs H5. springs 96 (which are eontrolled by the rotary magand the springs winding to the battery lead 80. Thus upon the dei nergization of'the relay 40 after the last impulse is delivered to the vertieal magnet. the relay 95 remains energiztal and the eireuit ot the rotary magnet Ji l is elosed whit-h eirenit extends from ground G at the relay 39 through the springs 85, 9t), 37, 97. 98, 94-,- tlfl and and magnet 34 to the battery lead 80. The magnet 3-H, upon energizing, rotates the wipers one step and. by opening the spring eontaets 100 and 96, diseonneets ground G from itselt and from the relay 95. H the first trunk line oi the sew on'd level is idle, the relay 95 deenergizes as soon as the springeontaet 96 is opened. If this trunk line is busy, however, the

ate, wiper 32 finds the contact wln'eh it n gages provided with a guarding ground potential, which is transmitted to the relay 95 through, its springs 97 and 98 prevents it from deenergizing. net 34, however,

and'therehy The ma gthe first digit 2 of theand 7 are separated twice derfergizes .when the' spring Contact 100-.is broken, regardless of whether the relay 9.7 remains energized or not. It the relay 5).) remains energized. the eireuit of the rotary magnet will be again it-loseil as soon as its armature drops bark tar enough to rlose the rontaets ltltl and am. The rotary magnet will theret'ore operate in a manner similar to that of a buzzer to advanee the wipers step by step over the eontarts until the non-grounded rontaet of an idle trunk line is reaehed by the wiper 33, whereupon the relay H5 dei nergizes. The relay 1 3. upon dei nergizing. whether after one orsevera'l operations of the rotary magnet. -a-rinanently breaks the eireuit oi the magnet Ill and eloses the eireuit ot' the switehing relay ltll. whieh rireuit extends iron: ground ti through the springs 8:7 W. 37. HT. 102 and'the relay ltll to the battery lead The relay 1H1. upon energizing. diseonneets the line relay 3.? from the line and extends the line eonllertion over the heavy ronduetors shown through the wipers Ill) and Ill to the see'ond seleetor I The line relay 103 of the switeh I thereupon beeonies energized and eloses the rir euit ot'the relay 101, whirl) in turn, upon energizing. eompletes a eireuit extending from ground (l through the springs 105, wiper 32 ot' the switrh l) and springs 97 and 1 2 and relay 101 to the battery lead t). This eireuit maintains the relay 101 energized after its original energizing eir- Hill is broken by the relay li whieh de energizes shortly after the line relay 3.") is diseouneeted from the line. The relay 104 ot the seleetor l also maintains a guarding ground potential upon the private bank eontarts ot' the trunk line in the banks ot the lirst seleetor switehes ll whieh have aeeess thereto.

When the substation railing devire is operated tor the seeond digit 2. the seleetor l operates in the same manner as explained torthe seleetor l) to extend the eonneetien over the trunk eonduetors 107, 108 and 1 to the eonneetor ll (Fig. 3). The line relay 51 ot' the eonneetor thereupon hvmonies energized and eloses the -ireuit ot the relay no. The relay 110, energizing, pro rides a holding eireuit or the relays 111, 101' and 12 ot' the switehes I It and (X respeetively. This eireuit extends from ground G at the eonneetor switrh through the relay 53. springs 112. eonduetor 109. wiper 113, thenee through the springs 114 and 115 and the relay 111 to the battery lead 80, and also through the eontaets 11(3 and 117. wiper 32 oi" the seleetor l) and through the relays 101 and 12 over the eireuits already traeed. The right-hand winding oi the meter magnet 29 is-also ineh ded in the e-ireuit with the relays above mentioned. The switehing relays 111 and 101 of the switehes l and E, the eut-otl' winding 12 ot' the switeh C and the right-hand winding of the meter in multiple magnet all have a comparatively high resistance as compared \vitlpthat ot the relay o l of the connector switch. so that the latter relay is not opcrativcly energized over this circuit. and therefore maintains the connec Since the relay lltl is slow acting it does not deencrgize during the momentanv interruptions ot' its circuit by the relay 51, so that ach time the latter relay is det ncrgized a circuit is closed extending from ground G through the spring 118 and its back contact, spring 119 and its trout ontact, relay lit), vertical magnet 14 and the side switch wiper 19 to the battery lead St). The vertical magnet -t-lreceives two impulses over this circuit and operates to raise the s'-"ltt'll wipers +11, 42 and +3 to a position opposite the second level of bank contacts. The relay 120, which is included in series with the vertical magnet, remains in its energized position during the entire time impulses are being transmitted through it and operates to close the circuit of the relay 122 and the private magnet 50. After the last impulse is delivered, the-relay 120 opens the circuit of the private magnet fit), which upon deenergizing permits the side switch to advance lrom first to second position. The

, movement of the side switch wiper it) from first to sci md position transfers the battery connection from the vertical magnet to the rotary magnet 4-5. now operates The calling subscriber his calling device tor the last digit 0, in response to which the. connector line relay 51 operates to transmit ten inipulses through the rotary magnet 45, in series with the relay 120, whereby the shaft wipers are rotated onto the contacts of the desired line. The relay 120 operates in respouse to this operation in the same manner as for the previous digit to cause the private magnet 50 to advance the side switch one more position-that is,ti'(nn second to third position afterthe last impulse for the digit is transmitted. By the engagement of the side switch wipers L6 and 4:7 with their third-positioncontact points, and by the deenergizath'm of the relay 122, the line con nection is finally completed with the called substation, as shown by the heavy conductors. The relay 122 controls the contacts in the line circuit and is made slow acting, so as to prevent the completion of the line con- ,nection until after the cut-oft winding 123 of the switch C has had time to operate the armature 123 .to disconnect the switch from the line. The circuit of the winding 123 is closed by the engagement of the connector side switch wiper 1-8 with its third-position contact point. said circuit extending from ground ti through the secondary winding ot the busy machine Q' back contact ol" the spring at, side switch wiper 4 private wiper 42-). back contact ot the spring 121: and

the winding 123 to the battery lead 80. The

connection of the ground ti with the coin nector private banlc contacts oi the alled line over the portion of the circuit just traced provides said contacts with a guarding potential to prevent the busy line from being seized by some other connector switch.

his line is provided with talking current through the windings otthe back-bridge relay 52 ot the connector switch, which relay, upon energizing, closes the circuit of the ringing cut-out relay 198, said circuit extending trom the battery lead through the side switch wiper t9. relay 12S, springs 129 and Y130 and the shaft-controlled contact 131 to grouml G. The relay 1'28, upon energizing. interrupts the circuit of the ringing relay 253 at the springs 126 and closes a locking circuit for itself through its own springs-132. imlependent of the springs 01 the lmch-bridige relay A further result of the energization oi? the relay 5; upon the response ol the 'alled subscriber is the transposition of the conlwctions between the windings ot the line relay 51 and trunk conductor-s10? and 10S whereby the direction of current in the calling line is reversed. This reversal ot' the current in the left-hand winding of the subscribefis meter relay 29 2) causes the two windings to assist one another and the armature is attracted to operate the meter to register the call.

-Atter the crmversation is completed "the connection is released by the hanging up n the receiver at the calling substation in following manner: N hen the receiver atlllc substation A is restored to the switch hook, the separation of the hook switch springs 73 and 74 destroys the energizing circuit of the connector line relay 51 (Fig. The relay 51 thereupon deenergizes and opens the cii cuit ot the relay 110. The relay 110, upon deienergizing, opens the holding circuits of therelays 111, 101 and 12- of the switches 13, and C, respectively at the springs 112 and bridges the ringing" the interrupter 125, relay the side switch wiper 19 to shaft contact 38 i The m'a net 250,

and also closes the circuit of the connector release magnet 250. The latter circuit extends from ground G" through thespring 118 and its back contact, spring 119 and its back contact. shaft-controlled contact 180 and the magnet 250 to the battery lead 80. upon energizing. restores the connector switch shaft and side switch to normal position, and its own circuit is interrupted at the contact 130 when the shaft reaches its lowest position. The deenergization otthe relays 101 and 111 of the switches l l and F serves to close the circuits of their respective release magnets -lfi'and 181. The

circuit for the magneti-it'r ot' the switch E extends from ground ti": through the springs 88. S9; 90. "1. spring 92 and its back contact, and the magnet ht) to-the battery lead 80. The circuit of the magnet 191 is similar to that of the magnet 36. The

circuits ot' the magnets '36 and 181 are broken when the switch shafts reach their normal positions. The deenergization ot the winding 12 of the swiitchC permits the-plunger arm ,9 and the armatuie 13 to restoreto nor mal position. 1

From the above description it is evident how connections are established and released in the automatic exchange.

It will now be explained how an operator may establish a connection between the mansubstation A (Fig. 3).

the telephone T signals the operator in the ha] telephone T (Fig. 4) and the automatic The subscriber at usual manner by operating the magneto 58,

whereby the line relay (KO'becomes energized and is locked in its operated position to close the circuit ot the lamp 112. The lockin, circuit toi the relay (30 extends from ground G through the back contact of the armature 1323, contact point 134. armature 135 and the right-hand winding of the vrelay (30 to the battery l3. The operator answers the call by inserting the-plug 1 into the jack J. whereby the calling line is connected with the cord circuit-aiul a circuit is closed from ground G through the contact 137, armature 138 and its back contact. sleeve oi the plug'l and the jack J and cut-oft relay (31 to the battery It. -The relay (31. upon energizing. disconnects the line relay from the line, breaks the holding circuit of the line relay and closes the eireuit of the busy signals (33. Upon learning thenumber of the desired subscriber, the operator inserts the plug P into a multiple jack J of an idle trunk line leading to a selector switch 1 in the automatic exchange, and 'operatcstlie key K to connect a calling dev ce similar to that at the automatic subscribers substation with the trunk. in Fig. 4 the calling device is represented diagrammatically by a pair of imulse springs 140. By the engagement. of the sleeve conductors ofthe plug 1? and the jack J a circuit is closed from grounclG in the has a sutiicientlv hi h resistance to revent sutlicient current from flowing over this circuit to energize the relay (38, but it is itself energized. as well as the relay 111. The relay 141 prepares the circuit for the lamp (36, which circuit. however, is still open at the springs 11:2 of the key K. The relay (3 upon ei'iergizing. closes the circuit of the busy signals T0. 'lhe'connection of the cord circuit with the selector 1 over the trunk conductors 14-5 and 116 causes the line relay 117 of said selector to energize in the'same manner in which the line relay of the selector I) (Fig. 2) was energized when the connection was first extended to it from the calling substation. The operator now operates her calling device in accordance with the respective digits of the number called tor. The selector T operates in response to the operation of the calling device for the first digit in the same manner as explained for the selector E ig. 2) to extend the connection to a second selector similar to the selector F (Fig. 2). This second selector operates in response to the impulses for the second digit to extend the connection to a connector switch. which in turn operates in response to the last two digits to complete the connection with the called line in exactly the same manner as when said switches are operated by. an automatic subscriber. as hereinabove explained. After the operator at the cord M has completed the operation of the calling device. the key K is restored to normal position. whereby the calling de vice is disconnected from the line and the polarized relay 7 is bridged across the talk ing circuit instead. The current which flows through the relay (S7 at this time is in the proper direction to maintain the contact 148 closed. whereby the circuit of the lamp (S0 is completed. said circuit extending from ground G through the springs 1-12 of the key K. contact 1t8. armatiire 198 and its front contact and the lamp (36 to the battery 11. Upon .the response of the called subscriber. the current in the polarized relay (3? of the cord circuit is reversed in the same manner inwhich the current in the automatic substation A was reversed. This re versal of current causes the relay ()7 to open the contact 118, wherebythe lamp 6G is extinguished to signify that the called subscriber has answered. It will be remembered that in the connection described between the tor I (Fig. 5) is completed through the relay '1 so 53 of the connector when the operator makes a call. The relay Ht) of the selector 1 has a low resistance as compared with the correbusy signaling machine Q.

spending relays of the switches F and E, so. that when the relay 14-) is included in the c1rcult of the relay 32-} .ot the connector. the latter relay is operatively energized and disconnects the busy signaling machine Q from the third-position contact point of the side after hanging up 'liisreceiver, operates the and opens a circuit at the back contact oi the-armature circuit of the lamp (35 at the removal the v former.

magneto 58. whereby the relay 182 in the cord M is energized momentarily to open the shortcircuit of the relay 182; at the con-' tact 137. l he relay led-thereupon becomes energized in series with the cut-ottrelay til second point in its own short- 138 and closes the the front contact of said armature. hen the called subscriber hangs up his receiver,

the connector b \cl\'-bridge relay 5? (Fig. 3) 4 (leiinergizes. whereby the current in the polarized relay tfi oi the cord M 'ish'estored tovits. normal position, causing said relay to elo'se'the contact H8 and again light the lamp 6t. 'lheom-i-ator now ljtll'lOYCStlltl plugs P and l t'rom the jacks. and upon of the plug l from the jack J the automatic part ol the connection is released in the same manner in which the connection between the substations A and A was released whenthe receiver at the substation A was hung up.

Having explained how' connections may be completed with an automatic. line either by aniautomaticsubscriber or by the operator, it will now be explained how connec tiop is preventtalfrom being made with a busy line -and how the operator is given i a distinctive busy signal to indicate whether thebusy line is involved in a local connection or has been called by an operator from manual switchboard. From the foregoing description it is' evident that whenever an automatic line is n'ector private bank contacts are provided with a guarding potentialthrough the secondary winding of a busy signaling transtial for calling ground G (Fig. 2) through the winding 86, While the guardmgpotential for called thence to the tactis oi' the busy line.

tacts ot' the busy line. thence in use its 0011 For example the guarding potenlines is suppl ed fromlines is' supplied either from. ground G" (Fig. 3) throughthe secondary winding o't themachine (V. or troin ground (i"through the secondary winding of the tl epending uponwhether-the line has been lcalletl by an Eitlttfllltltlt' subscriber or by an operiitor. Assume now that the connector ll (Fig. 3) attempts to connect with a busy line. \Yhen the slow acting relay 1-30 of the connectordei nergizcs ai'tei the last im pulse for the'last digit is delivered... the private magnet 50 and the relay 12; do not deenergize to complete the connection the called line it said line is busy. but this magnet and relay remain energized otter a circuit extending from the guarded private bank contact of the called line through the side swit h wiper l8 (in second position). springs lJt) and 13]. relay 15;. springs lFi-l and 152) and the relay l2! and magnet it) to. battery. Since the relay l2) and magnet 50 do not deenergize, the side switch remains locked in second position and'the connection between the ailing and the called lines is maintained open at the side switchwipers l-t' and 4?. as well as at thesprings oi the relay 1221 The relay 15; being included in the lock ing circuit otthe private magnet energizes and transfers the said locking circuit from the grounded private bank ground G" through the springs and the shalt-controlled contact 131. l pon the closure of the contact. between the '13? by the relay 152. a con nection is extended of the talking circuit through the'side. switch wiper l-T (in second position);

shat't wiper 42-).

springs "15? and 13h. side switch wiper -lS (in second position) private wiper l and busy signaling machine Q, Q, or'tQ", dependingupon which of these machines is connected to the private con Aril'cllit 'l'rom the busy signaling machine is therel'ore com pleted lrom ground through the secondary winding oi the connected machine to the connector private bark conthrough the private, wiper -1 ,ot the connector switch which has been used by the: operator, through the side switch wiper l8 (in sec ond position). springs lot) and. 15?, side switch aviper l7. condenser 15%. thence vover the heavy" conductors to the calling line and back over the other side ot the line. through 'the upper winding ot'the connector line relay 51 to the battery lead St) and thence. to the battery 13 and ground backyto the busy signaling machine. A busy signal is thus given to the calling subscriber.

In order for the operator to .letermine whether or not the called. line is busy, she operates her key K (Fig. 1) to connect her talking set with the line after the conneo machine Q,

with.

contact '-to' 151 and 1;)?

from the lower side busy signaling i called by an auto 'atie siibscribeig I, through which the tion has been completed, whereby a path for ,the busy signal current is furnished through the operators receiver. It the busy line is a calling line. the operator will hear the busy signal produced by the machine (Q (*ig. '2). If it a line which .has been the busy machine signal heard wilt be that of the IQ. (Fig. 3), while it the liiie has been called by an operzdor, the busy signalwill be that produced by the iiiael ine Q. he operator, upon noting the characteristics of the dit ferent busy signals. 'enablcd to tell in what kind of'al connection the called line is engag l. If thesig'nal from the machine Q 's heard. the operator knows that the line called for is busy in another connection'. from the manual switchboard, long distance calls are completed, Wlillt? chineQ or (Q is heard, sheknows that the line called tor is involved in a local conliccti oil.

i arranged to pro- ,1 it. is not so desired, theniachines Q and Q may give the same kind of a busy signal forboth calling descr ption a circuit is closed from signal. or a single machine may be used to producethe in local connections.

If it is found that the line is busy in a toll or semi-automatic connection. the operator informs thefcalling subscriber that the line is busy. If. however, it is found that the line is busy in a local connection, the operator then inserts the plug 1* into a jack J (Fig. ti) leading to a connector X, which has access to the particular group "of lines in which the busy called subscriber is located,

and calls him again over this connector to inform him that she has a toll or semi-automatic call waiting. The operations ol the'connector N, in so far as liiuliiig the called line is concernial, are the same as those of thecounector ll (Fig. 3), and itis therefore. uni'iecessary torepeat a of these oi ierations. When,

however, the. wipers engage the contact of said line. the'opcration is somewhat dil' 't'erent. Upon the engage'iiient ot the private wiper ltit) with called line, which is assumed to be busy, I said contact through side switch wiper l6l.(in second position) and the relay '10: to the battery lead' N23. The relay I62, upon ener gizing, extends a connection from ground G" through the springs ltit and H35 and the relay 'ltiti to the spring 167 of the-p'rivate magnet relay 168. 'When this relay d'ethe wiper 160,

'energizes-alter the last impulse for the. last digit is delivered, the above circuit is continuedihrough the spring H39 and private magnet 170 to the battery lead 163, thereby it the signal from the nia- If it is desired to distinguish be-' ,tween calling anilcalled. lines, the two ina- I chines Q and Q" may b duce signals o'fdit'l'erent characters, while it and called lines the contacts of the locking the private magnet 170 in its ener gized position to prevent; the side switch from passin; to third position, while at the same time the relay use is energized. The relay ioe corresponds in its 0 ie'ation to the relay 152 of the connector l-l (Fig. 3). but has a somewhat dili'erent function. The relay lot). upon energizing, .does not connect a busy signal relay with a calling line, as does the relay 15; nor does it shift the holding circuit from the private magnet away from the circuit controlled by the private wiper 1(it) but it does. by the closure of the contact between the springs I'll and 172 and 17:3 and 1H. complete eonnection between the calling and called lines by way of the second-position contact points manner. andalso completing the circuit of the ringing relay 177 at the side switch wiper 1T8. Ringing current will thereupon be applied to the called line and. the subscribcr will be signaled in the usual manner. It will be seen that the locking circuit for the private magnet. is controlled through the medium of the slow acting relay 1G2 instead of directly from the private wiper, as is the case in the connector ll (Fig. 3). This is to prevent the side-switch of the connector ll from passing to third position immediately upon the renio 'al of the ground from the private wiper 1(itl,'so as to give the former connection sullicient time to he completely released before the side switch. wiper 1G1 reaches third position and connects ground ti with the contacts of the called line. It' the local connection had been released before the connector hadfound the line. its side switch would have in1- iiie'diately passed to third position in the usual manner. After the connector N has begun to signal the called subscriber, the ringing current is cut oil' upon the removal of his receiver in the usual niannerthat is, the back-bridge relay 1T8", upon energizing, causes the ringing cut-out relay 179 to be"encrgized.

, After gettinginto communication with the desired subscriber through the inediuin magnet 170, which and permits the side v point of the wipers 175 and 176 in the usual I i a resistance 191,

line will'bc grounded 'lo the machine Q, but

' 2H0 ol' the side switch wiper forms him that she; has a call for him from the manual or long distance line and can then either let the two subscribers talk through this-connector, or can request the called subscriber to hang up his receiver and she can then call him again through one of the regular connections. mode. of operation is advisable in that the special connector N does not remain in use during the conversation, but is always in condition for use in calling a .busy line.

The connector switch 11 (Fig. 7) is a modification of a connector coniplishing the same results as the con.- ncctor 11 (Fig. 3). The connector H is very similar to the connector H, with the addition of the relay 190. The relay 191 of the connector H corresponds to the relay 53 ot' the connector 11. Instead of controlling the.connection oi busy signaling inach'ines with the third-position contact point 193. of. the side switch wiper 192, however, the relay 191 controls a short-circuit around through which said contact point is permanently grounded. Since the relay the relay 53 (Fig. itis evident that when one automatic subscriber is called by another automatic subscriber through the con- "nector H, the relay 191 will not be energized and the private bank contacts of the called direct without any interposed resistance, $1 4. is short-circuited by the springs 195 and 196. When, however, an automatic line is called, by the operator, "the relay 191 is energized and the resistance 191 isthercfore inserted inthc groundconnection oi the tonnc('tor private bank contacts oi the called line. The "relay 190 controls the connection hetw cti'i the, spring 197 of the busy test relay [UH and the busy signaling machines Q, and ilhwvhich correspond to the machines t1 ii -rd Q tl ig. 3).' Normally this spring if)? is connected througl'i the spring 216 when the relay 190 416 is shifted intois energized. the spring and the machine 'ontact. with the sprin'g .213

Q" is thus connected with the spring 197.

"l 'h lower winding of the relay 190 is in llit'lill in the onnection between the spring 11)!) and the secoitil-position contact point 1!)1, while the upper winding ol' said "relay tilt) is included in the connection between the. spring 201 and the SlHl'tt-(Ulitl'Ullctl contact 2012, but is normally short-circuit-'hl through its own springs 2 and 301. nicnt, it will be seen tliat'ihc lower winding ol' the relay 100 is included in the original cncrgizing' ircuit ol' the relay l is'whcn the rclay N ili-,- ii rgiz s a l ter the last. digit of a liusy numb-1i has been ca-llcd. This cir uit estei'nl.-i' :i'mi the grounded private bank contlift oi (heralletl line through the.

private wiper private bank contacts otthe This latter switch for ac- 1'91 operates in a manner similar to since the resistance omitted fl 10H] With this arrange relay 191 206, side switch wiper 19-2, contact 200, lower winding of ,the relay 190-, springs 199 and 207, relay1'98, springsQiT and 21S, relay 210 and the private magnet 211 to the battery B.

alled line are direct, the relay 190 connected to ground circuit and connects is energized over this the busy signaling machine Q with the'callmg line through its SPI'HIQSQ15 and'21ti and the springs 197 and 208 of the relay 198, and at, the same time removes the short'circuit from around itsown upper winding lay-separating the springs 203 and 201.2 The upper winding of saidv relay istherefore included in the loclt'ing'circuit of the relay 198, which circuit? may be traced troin'. ground (1 througln the 'shal t-controlled contact 202,

upper winding otthe relay 190, springs 201 and .204 and thence througlr the i-elayslQS, ,210 and magnet 211, as

If, however, the private bank contacts of It the connector the called line are grounded through a resistan'ce similar cient current does not flow through the lower winding of the relay 190 whenthe-relay .205 d'eene'rgizes to close .the circuit 'ot' the relay 198. Since this relay is not energized by this cuit 18 not removed from its upper winding,

so that it is not included in the locking of the relay 198, and the busy signalingfma- I connected vthrough the spring 19 andt-he busy signal chine Q. therefore remains.

It is thus adapted to is furnished bythis machine. seen that: the COIIIlOt'tUl' it, is

to the resistance 194:, sufii-.

initial circuit, the short-cirsend back a discriminating busy signal to the calling lines without requiring the busy ione current to be connected to the connector. private banlccontacts of the called line, as is the case with the connector [I (Fig. 3). \Vhcn a subscriber endeavors to -ibtain'connection with the telephone ot' a Ci lllill fl; subscriber, the busy tone isof the same character as that sent over the line whenthe desired subscriber is being called by another automaticsubscriber, (1., the tone from the machine (JP 1 the t'(' llo\\-'ing manner: When the connectors 11 are employed in thesystem, the spring contacts 24, 2.5 and 2t) v.(Fi

the subscribers' individual switches and the cond lctor 23 maybe con-' nccted directly to the line switch bank spring '16. The connector.private bank contacts ol the callinglin s will. therefore. be guarded by the sanic ground that supplies the hold ing circuits for the selector switches -thal'. is, thcyavill be grounded through the. relay 19L (Fig. 7). Since the resistance otthe is negligible. the connector private bank contacts of calling lines will in cll'ect be grounded direct. and when the connector ll 2 ttcnipts to make connection with a busy calling line, it will operate in exactly the This is accomplished H1 2) may be in this second position.

scriberhangs up so same manner as when connection is atsubscriber.

It will thus be can ascertain whether or not the busy called subscriber is involved in a toll connection or in a local connection. will be seen that this differential busy test depends solely upon the .manner in which the connection'has been extended to the connector which first connected with the line, and is obtained even though the same kind of a connector is employed for attemptingto establish connection with the called line while it is busy. If this connection has come by way of the automatic exchange, in which the regular selector switches are employed, one character of busy test is .produced, while it this'connection has come by \vayof the toll operators board, in which a different form of selector is employed. a ditferent character of busy test is obtained. lVhile I have described busy test as being employed in a system in which the toll calls come through a manual board and the local calls are cstablisln-dcntirely by automatic means, it will, of course, be understood that the local calls could like wise come through a manual board, the only requirement being that in local calls a se-' lcctor is used having a relay in the holding circuit of one resistance,.while in the long distance calls a selector is employed having a release relay of a different resistance, to thereby bring about the marginal action or the connector relay. H Furthermore, in connection with the connector switch shown iii-Fig. 6, it will be seen that I have devised a very etiicient switch for calling in on a busy line, which switch is provided with means for locking its side switch in second position and con'ipleting the talking connection while the side switch is Also, if the subas to. release his line while the operator is attenuating to make connection through this form of cmlnector switch, the

in the usual manner and the scribers line to call the subscriber baclc to his telephone. i

' acter to scriber.

and will, therefore, appear at the connector connector H.

seen that I have devised a very efficient system in which the operator a diflerent signal from Fm'therm'ore, it 7 this discriminating switch for seizing for extending a connection from automatic line to sule switch is then stepped to third position ringing current is sent over the called sub may call a second circuits of these three lines,-

private bank contacts of these lines, as for example, at private Obviously therefore. an operator calling throughthe connector H may in succession call these three lines and obtain each one, indicating to the op'e ator three diti'erent characters of connection. From the foregoing it will also be seen that the connector N may be provided with multiples of the private contacts of three different-lines and it will further be seen that connector N is of such a special character that it any one calling any onev of these three lines \ia said connector while said line is busy remains on the line called until the original connection is tern'iinatcd, the side switch of the connector N will pass to thirdposition. applying a guarding potential to. the line called and also a tone through the private-wiper ot the same character-as that produced by the signaling machine Q".

iVhile I have illustrated and describml one particular embodiment of my invention, it-will he understood of course, that I do not wish to limit myself to the exact con-' struction shown and described.

.lVhat I claim as my invention is 1. In a.telephone system, a called line, a connector switch for seizing said line, a plurality'ot means for extending a connection to said connector switch, a second connector switch, andmcans for giving a dis-' eliminating busy test -f()l-lll(li(7tltlll the means employed fox-extending the connection to said first connector switch when said first connector switch has seized said line to make conncction therewith.

2. In a telephone system, a calling manual hne. a calling automatic line,'a called automatic line," an automatic.connector said main ualline to said connector switch, means for extending a connection from said calling means for operating said connector to seize Said called line, and a discriminating busy test for indicating which line. is connected with saidconnector;switcln 3. In av telephone system, a. plurality oi calling lines, a called line, an automatic con -ncctor switch. for seizing. said called line,

means torextcnding' a connection from one of said calling; .incs to said connector switch, means for operatingsaid connector to seize said called line. independent means for extcnd ing a connection 'lronrauothcr (l said calling lines to saidswitch, and a discriminatint, busy test for indicating-the calling, line with rwhich. said connector switch is connected when an attempt is made to connect with said. busy called linc.

in a-tclcphonc system, a pair ol calling bank contacts of the said called line, means 1 sa id connector switch', I

called line. in

.heen established from the other including a plurality of {For extending a connection lroin said calling to said connector switch.v

for eXtending -n'i.eans' Silltl busy 2 ti ple means including a automatic line lines. a called line. an automatic connector switch. means including a selector switch for extending a connection from one of said calling lines to said ctninector HWItCILlD 3115 including another selector switch for extending a connectio p from the calling lines to said"connectorswitch. means for operatingsaid connector and incansjt'or placing a discriminating busy test on th'cvinultiple contacts of said called line to indicate which (it said calling lines is connected,with said conneetor. i I

.3. In a telephone system. a pair ot-calling lilies. a called line. an auton-iatie connector switch. means including a selector switch a 'coniiection"from one of said to said connector switch. ineans calling lines including another selector switch for extenda connection.trom the second of said calling said connector s\\'itcli.-means t'or ing linesto tageratin'gsaid connector line. a pair ol busy for eonnectingone or the other of signaling machines with the mulcontacts of said called line. depending upon which of said calling lines is connected with. said. connector. d In -a telephone calling lines. a called line. an ncctoc'switcli. means forextending a connection from the tirst. group or' said calling lines to said connta'tor switch. means for extending a connectionfrom said second group "of. calling lines'to said coni'iector means for operating said connector to seize saidcalled line.

system. twb groups of a pair of busy signaling machines. a second connector switch means w liei'el a busy signal from one at saidbusy? signaling machines is'transmitted through said second. connector switchwvhen it attempts to make. connectioiiwith thebusy called line when connection has been established with said first connector switch from one of said groups-of. linesJand means for transmitting a busy signal from the other of said busy mach oi said groups of lines.

7 In a telephone system. a calling manual line. a calling automatic line. :1 called autoiuatic line. an automatic connector 'sw .nianual operatofs cord circuit for extending a connection from said itcn,

said connector switch. means automatic switches manual line to means l'or operating said connector to seize said called line. anda discriminating busy test for indicating which means is employed t'or connecting to said connector \\'lt(li when an attemptis made to establish onnection with said busy called hue.

second of said conne tion to se ze said I .line in a previously establ means tor giv to seize said called' signaling machines. and

automatic conbusy current machine.

switch,

mes when said connection has S. In a telephone system. subscribers lines. nieans tor-establishing a connection between two of said line-sJmeans for giring one character o-t busy test when an attempt is Illilt with a called line and means forgiving a dillerent character of busy test when an attempt is made to establish connection with a alling ishe d connection. a source ot sigsaid last means comprising also a device naling current and comprising for appropriating the same to ing line before it is called.

a. In a telephonc s \'stem. manuallines. automatic lines. means for establishing connection between any two of said lines. and i ing a t'liscriminating busy test.

when an attempt is'nindc to connect with a line already in use to indicate whether said busy line is a calling or a called line in the establishedconnection. said last means coniprising a source'ot' signaling current and comprisingalso a device for appropriating the same to the calling line when calling and betore it is call'ed leto establish connection involved in a previous the said call--.

10. In a telephone si'steni. subscribers.

lines provided with nail sa d term means for. :alling extending a connection from said lines. a necting said machine \\'ltli said multiple terminals when said connection is extended, and betore the l ne is (ralledfi.

tiple te'rniinaIs, inals. means for and means for con 9 a plurality of'fi 11. In a tel'ephone system. a subseribcns multiple terminals. means erminals'. trunk lines. a trunking switch tor said subscrihefs line for extending a connection over oneot said trunks. a busy signaling machine. and means 't'or coiinecting said bnsy'signaling machine with said. mu'tiple termim'il's when said trunking switch is operatedto connect with one of said trunks. and be 'alled.

12'. In a telephone system. a subscribefs. line, multiple terminals for iunnericaltrunking switch individual .1 o said lllitflit'lilili lines. means controlled by said. subscriber iii nialiing a..cal-l to operate said switchto automatically select an idle one of said trunks. a busy signaling machine, and means controlled by the operation of said switch for connecting said busy signaling machine with Htl'ltlllillltlldt terminals.

12). In a telephone system. a pair'ot call-r ing lines. a .called line. aii.=-ruLoinat-ic c-onnector switch. means inclin-ling a selector switch for extending a connection from one otsaitl calling lines to said connector switch, means. including another selector switch for extendii-ig a connection from the second'of said calling lines to said connectorswitch, means l'oi operating said connector to seize line provided with 'for calling sai'd t said line. a non-' of said machines I 16.111 a telephone system, subscribers" nection is established from said selector said connector rclay being adapted, to be connected in relay,

one of said selectors and a Said called line, a busy signaling machine ,normally selected for use. a second busy lines. an automatic connector switch for con necting with the lines of one of said groups, means including.aselect'or switch for extending a connection from a liiie'ot' one of said groups to said connector, means including another selector forextending a conne tion from a line of. the oth r of said groups to said connector, a marginal relay in said connector. a loyy resistance relay in one ot said selectors and a high resistance relay in the other of said selectors. means tor connecting the relay ol one of said selectors in series with the connector relay when a coni to the connector, opcratively energized when but not-when connected in series with said high resistance relay. :1 pair of busy signaling machines, and means controlled bv Said connector relay for bringing one oi the other ot-said machines into use.

15. In a telephone system, two groups of lines, an automatic connector switch forconnecting with the lines of one of said groups, means includinga selector switch for extendiiig a (miner-thin from a line of one ot said groups to said connector, means including another selector for extending a connection from a ,line ot'tlie other relay in said connector. :1 lowresistance release relay in high resistance release relay in the other ot said selectors. means tor coniiecting-tlie release relay ot one of said selectors in series with the connector relay when a connection is established from said selector to the connector. said connector relay being adapted to be opt'a'atively en ergized when connected in series with said low resistance release relay, but not when connected in series with said high resistance release relay, a pair of busy signaling niachines, and means controlled by said coii-' bringing one or into use. I

nector relay for the other lines divided into groups, a connector switch having a motion to select groups and a second-motion to connect with a line in a selected group, a plurality aconnection t o'said connector switch, a second connector switch, and means for giving a discriinimiting busy testfor indicating the series with said low resistance of said groups to said connector, a marginal of means for extending to said first connector group, means including a connection switch when said end connector switch attempts to make connectionwith a busy'line.

1?. lo a telephone system. a plurality ot groups ol automatic connector tion to select groups means employed for extending manual lines, automatic lincsfan switch having a nio and a motion to connect with a line in a selected group. means for extending a connection from said maniial lines to said connector switch. meaiisjl'or extending a connection troni said lines to said connector switch, and a disci'iniinating busy test t'or indicating whether a manual or an automatic line is connected with said connector switch.

in. In a telephone system. a plurality ot' lines divided into groups. an automatic con ncctor switch having a, motion to select groups and a second motion to connect with a line in a selected group. ing a connection t'roni one lines to said connectorswitch. independent means t'or extending a ('tiliti tclltili troin another ol' said groups ol lines, to said connector switch, and a discriminating busy test for indicating the group ot' the calling line which is connected with said connector switch.

1!). In a telephone system, a plurality of groups ollines, an automatic connector switch having a motion to select groups and a second motion to find a line in a selected a selta-tor-switcli 't or *t'rom one ot' said connector switch, another selector switch for a connection from a second (it means l'or extendol' said groups of extending a connection groups of lines to said means including extending said groups of lines to said connectorswitch,

means for and means for placing a discriminating busy 7 test on the multiple contacts ot the line with 'wliicli said connector is connected to indicate in which of said groups the calling line bclongsw. i a i 20; In a telephone system, a ])lllItllllL\/ ()l groups of lines, an automatic connector switch having a motion to select groups and a second motion to that a line in a selected group, means including a selector switch for extending a connection from one of said groups of lines to said connector switch, means including another selector switch for extendinga connection from a second of said groups ot lines to said connector switch, a pair of busy signaling machines, and connecting one or the other of said busy signaling machines with the multiple contacts of the line with which said connector is connected, depending upon in which of said groups the calling line heautomatic connector switch having a motion sec-' aiitoinat ic' 

